diff --git a/.github/linters/.isort.cfg b/.github/linters/.isort.cfg
index f238bf7..1d877d0 100644
--- a/.github/linters/.isort.cfg
+++ b/.github/linters/.isort.cfg
@@ -1,2 +1,3 @@
 [settings]
 profile = black
+known_first_party = auth,contributor_stats,contributors,env,json_writer,markdown
diff --git a/.github/workflows/super-linter.yaml b/.github/workflows/super-linter.yaml
index e556867..06b030d 100644
--- a/.github/workflows/super-linter.yaml
+++ b/.github/workflows/super-linter.yaml
@@ -39,7 +39,7 @@ jobs:
       - name: Install dependencies
         run: uv sync --frozen
       - name: Lint Code Base
-        uses: super-linter/super-linter@4ce20838b8ab83717e78138c5b3a1407148e0918 # v8.7.0
+        uses: super-linter/super-linter@2da136927bd4a73596db63044b504547c62cb854 # v9.0.0
         env:
           DEFAULT_BRANCH: main
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/Dockerfile b/Dockerfile
index 5200cce..5195c31 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -25,7 +25,7 @@ RUN uv sync --frozen --no-dev --no-editable \
 
 # Add a simple healthcheck to satisfy container scanners
 HEALTHCHECK --interval=30s --timeout=10s --start-period=10s --retries=3 \
-  CMD python3 -c "import os,sys; sys.exit(0 if os.path.exists('/action/workspace/contributors.py') else 1)"
+  CMD ["python3", "-c", "import os,sys; sys.exit(0 if os.path.exists('/action/workspace/contributors.py') else 1)"]
 
 ENV PYTHONUNBUFFERED=1
 ENV UV_LINK_MODE=copy
diff --git a/contributor_stats.py b/contributor_stats.py
index e7ae283..65d1617 100644
--- a/contributor_stats.py
+++ b/contributor_stats.py
@@ -12,8 +12,6 @@
 # ]
 
 
-from typing import List
-
 import requests
 
 
@@ -101,7 +99,7 @@ def merge_contributors(contributors: list) -> list:
     Returns:
         merged_contributors (list): A list of ContributorStats objects with no duplicate usernames
     """
-    merged_contributors: List[ContributorStats] = []
+    merged_contributors: list[ContributorStats] = []
     for contributor_list in contributors:
         for contributor in contributor_list:
             # if the contributor is already in the merged list, merge their relevant attributes
diff --git a/contributors.py b/contributors.py
index c71683c..ad790bb 100644
--- a/contributors.py
+++ b/contributors.py
@@ -1,8 +1,7 @@
 # pylint: disable=broad-exception-caught
 """This file contains the main() and other functions needed to get contributor information from the organization or repository"""
 
-from datetime import datetime
-from typing import List
+from datetime import datetime, timezone
 
 import auth
 import contributor_stats
@@ -102,7 +101,7 @@ def main():
 
 def get_all_contributors(
     organization: str,
-    repository_list: List[str],
+    repository_list: list[str],
     start_date: str,
     end_date: str,
     github_connection: object,
@@ -166,8 +165,8 @@ def get_contributors(repo: object, start_date: str, end_date: str, ghe: str):
             avatars: dict[str, str] = {}
             counts: dict[str, int] = {}
             for commit in repo.get_commits(
-                since=datetime.fromisoformat(start_date),
-                until=datetime.fromisoformat(end_date),
+                since=datetime.fromisoformat(start_date).replace(tzinfo=timezone.utc),
+                until=datetime.fromisoformat(end_date).replace(tzinfo=timezone.utc),
             ):
                 login = getattr(commit.author, "login", None)
                 if not login or "[bot]" in login:
@@ -201,7 +200,7 @@ def get_contributors(repo: object, start_date: str, end_date: str, ghe: str):
                     "",
                 )
                 contributors.append(contributor)
-    except Exception as e:
+    except Exception as e:  # noqa: BLE001
         print(f"Error getting contributors for repository: {repo.full_name}")
         print(e)
         return None
diff --git a/env.py b/env.py
index 8b7bf6c..a36c631 100644
--- a/env.py
+++ b/env.py
@@ -63,7 +63,9 @@ def validate_date_format(env_var_name: str) -> str:
 
     pattern = "%Y-%m-%d"
     try:
-        datetime.datetime.strptime(date_to_validate, pattern)
+        datetime.datetime.strptime(date_to_validate, pattern).replace(
+            tzinfo=datetime.timezone.utc
+        )
     except ValueError as exc:
         raise ValueError(
             f"{env_var_name} environment variable not in the format YYYY-MM-DD"
@@ -88,8 +90,16 @@ def validate_date_range(start_date: str, end_date: str) -> None:
 
     pattern = "%Y-%m-%d"
     try:
-        start = datetime.datetime.strptime(start_date, pattern).date()
-        end = datetime.datetime.strptime(end_date, pattern).date()
+        start = (
+            datetime.datetime.strptime(start_date, pattern)
+            .replace(tzinfo=datetime.timezone.utc)
+            .date()
+        )
+        end = (
+            datetime.datetime.strptime(end_date, pattern)
+            .replace(tzinfo=datetime.timezone.utc)
+            .date()
+        )
     except ValueError as exc:
         raise ValueError(
             "start_date and end_date must be in the format YYYY-MM-DD"
diff --git a/markdown.py b/markdown.py
index 08b9250..a40b276 100644
--- a/markdown.py
+++ b/markdown.py
@@ -187,12 +187,10 @@ def get_summary_table(collaborators, start_date, end_date, total_contributions):
             )
         else:
             new_contributors_percentage = 0
-        summary_table += f"| {str(len(collaborators))} | {str(total_contributions)} | {str(new_contributors_percentage)}% |\n\n"
+        summary_table += f"| {len(collaborators)!s} | {total_contributions!s} | {new_contributors_percentage!s}% |\n\n"
     else:
         summary_table = "| Total Contributors | Total Contributions |\n| --- | --- |\n"
-        summary_table += (
-            f"| {str(len(collaborators))}  | {str(total_contributions)}  |\n\n"
-        )
+        summary_table += f"| {len(collaborators)!s}  | {total_contributions!s}  |\n\n"
 
     return summary_table
 
diff --git a/test_auth.py b/test_auth.py
index 9b907a6..3c8102e 100644
--- a/test_auth.py
+++ b/test_auth.py
@@ -3,10 +3,11 @@
 import unittest
 from unittest.mock import MagicMock, patch
 
-import auth
 import requests
 from github import GithubException
 
+import auth
+
 
 class TestAuth(unittest.TestCase):
     """
diff --git a/test_contributors.py b/test_contributors.py
index f15fd3f..a865344 100644
--- a/test_contributors.py
+++ b/test_contributors.py
@@ -2,7 +2,7 @@
 
 import runpy
 import unittest
-from datetime import datetime
+from datetime import datetime, timezone
 from unittest.mock import MagicMock, patch
 
 import contributors as contributors_module
@@ -34,7 +34,8 @@ def test_get_contributors(self, mock_contributor_stats):
 
         self.assertEqual(len(result), 1)
         mock_repo.get_commits.assert_called_once_with(
-            since=datetime(2022, 1, 1), until=datetime(2022, 12, 31)
+            since=datetime(2022, 1, 1, tzinfo=timezone.utc),
+            until=datetime(2022, 12, 31, tzinfo=timezone.utc),
         )
         mock_contributor_stats.assert_called_once_with(
             "user",
@@ -144,7 +145,8 @@ def test_get_contributors_with_single_commit(self, mock_contributor_stats):
 
         self.assertEqual(len(result), 1)
         mock_repo.get_commits.assert_called_once_with(
-            since=datetime(2022, 1, 1), until=datetime(2022, 12, 31)
+            since=datetime(2022, 1, 1, tzinfo=timezone.utc),
+            until=datetime(2022, 12, 31, tzinfo=timezone.utc),
         )
         mock_contributor_stats.assert_called_once_with(
             "user",